The invention relates to a method of assembling a cap with one end of a housing container, a cap designed for this method, as well as a housing container and a resultant container system, of the type described as an example of the invention. The invention further relates to a housing container for inserting a separating device in its interior, of the type described as an example of the invention.
Various container systems comprising a housing container and a closure device which can be coupled with it are described in patent specifications EP 0 867 378 A2, EP 1 174 084 B1, EP 1 174 085 B1 and U.S. Pat. No. 6,017,317 A1. In these instances, a coupling mechanism in the form of a thread arrangement between the closure mechanism, in particular the cap, and the end of the housing container to be closed is described, and the thread arrangement has thread segments in the region of the housing container distributed about the circumference, which are respectively spaced apart from one another in the circumferential direction. Disposed in the region of the internal face of the cap is the sealing mechanism comprising several layers, with a layer which can be closed again, a connecting layer between it and a gas barrier element as well as another connecting layer between the gas barrier element and the housing container. The re-closeable element is also glued into the cap by means of a hot-melt adhesive. This being the case, the connecting or retaining force of the other connecting layer between the gas barrier element and the housing container is not as strong as the connecting force of the hot-melt adhesive disposed between the re-closeable element and the cap. In order to guide and pre-position the cap with respect to the threads on the housing container, guide projections are provided inside the cap, which, as viewed in the circumferential direction, are shorter than the gap between the individual threads. The process of joining the cap to the housing container therefore involves imparting a rotating or pivoting movement to the cap.
Other closure mechanisms made by this applicant are known from patent specification EP 0 915 737 B1, for example, in which the conical seal element is inserted in the base region of the housing container and is retained in a clamped arrangement by means of a cap engaging in the outer periphery of the housing container in order to provide an adequate seal. The coupling is obtained on the basis of a pure snap-fit operation between the closure element which is similar to a cap and the housing container.
Another closure device made by this same applicant is disclosed in EP 0 445 707 B1 or U.S. Pat. No. 5,294,011 A, whereby a coupling mechanism is disposed between the cap and the seal element, comprising projections on the internal surface extending in the direction toward the longitudinal axis in the region of the cap and a shoulder projecting alongside the seal stopper. An additional retaining ring is also provided between the flange-shaped shoulder of the seal stopper and the projection of the cap disposed farther away from the housing container. In order to fit or screw the cap on, guide webs or threads are provided on the internal face of the cap, which co-operate with guide projections on the housing container. Accordingly, the cap can be fitted by means of a screwing operation by effecting a relative rotating movement between the cap and the housing container, or simply by pushing the cap over the guide projections on the housing container.
Finally, other closure devices made by the same applicant are disclosed in patent specifications EP 0 419 490 B1, U.S. Pat. No. 5,275,299 A, U.S. Pat. No. 5,522,518 A and U.S. Pat. No. 5,495,958 A. These documents disclose a coupling mechanism between the cap and the housing container on the one hand and another coupling mechanism between the cap and the seal mechanism disposed in it. The coupling mechanism between the cap and the housing container is again provided in the form of guide projections in the region of the housing container and guide webs which can be located with them, for example threads, on the cap internal face. The screwing-on movement is continued until the cap has been fitted far enough onto the open end face of the housing container that the guide projections of the housing container are moved into the free space between the end of the guide web or thread and the end wall of the cap. As a result, the cap can be freely rotated relative to the housing container without the coupling mechanism locating. Again in this instance, the cap can be fitted by a screwing operation or by pushing the cap incorporating the guide web over the guide projection or guide projections on the housing container. This is possible due to the elasticity of the cap.
Patent specification EP 0 753 741 A1 discloses a holder device with a housing container which has two ends spaced apart from one another in a longitudinal axis, at least one of which is provided with an orifice. The internal dimension of the housing container in the region of the first open end in the plane oriented perpendicular to the longitudinal axis is bigger than the internal dimension in the region of the other end in the plane oriented parallel therewith in the same spatial direction. In addition, an annular component is inserted in the open end, which covers the open end face of the housing container with a collar, and a cylindrical wall part projects in at least certain regions into the interior of the housing container. Adjoining the cylindrical wall part, the annular component has a step and a and region which is wider in cross-section region joined to it, on which the elastic seal element of the separating device is supported in the initial position. In the centre, the separating device has a cut-out, which is closed by a thin cover plate in the region of the top end of the housing container. The individual components are assembled and in particular the separating device is inserted in a vacuum chamber because once the separating device has been fitted, it is no longer possible to access the interior without damaging the latter. A film is also glued onto the collar-shaped shoulder of the annular component and a cap is fitted. The interior is filled by piercing the thin cover plate of the separating device, the thin film as well as the cap. During this filling process, a vacuum is created in the interior, as a result of which air is also sucked into the interior. This is followed by a centrifuging operation, during which the separating device moves out of the annular component in the direction of the closed end so that it lies with its seal element also in contact with the internal surface of the housing container. The settlement speed in the mixture and the elements already separated is determined by the contact force of the elastic seal element on the internal surface. Depending on the selected density of the separating device as a whole by reference to the elements in the mixture which have to be separated, the mixture floats at the separation surface between the two media of differing densities. During the centrifuging process, it is possible for the lighter medium to get between the internal surface of the housing container and the elastic seal element.
Another container system with a separating device is disclosed in patent specification EP 1 005 910 A2 and has a cylindrical housing container with a virtually constant internal diameter. Disposed at the open end of the housing container is a closure device which can be pierced, and the separating device is disposed almost in contact with it, including in the initial position. This separating device is made from a flexible rebounding material and a sealing device is provided on the outer periphery of the separating device in order to seal the internal surface of the housing container. In addition, another deformable element is inserted in the interior, which is pressed against the internal wall of the outer housing container due to the pressure exerted by the medium as a result of the centrifugal force and thus forms a flow passage between the separating device and the inserted deformed insert part so that a sealing position in conjunction with the seal elements disposed on the separating device is assumed again once the centrifugal force is switched off, thereby enabling the separated media to be kept separate from one another.
A container system for a mixture of at least two media is also known from patent specification DE 195 13 453 A1, which has a housing container in the form of a test tube closed off by a closure device at an open end region and in which a separating device is inserted for separating the different media of the mixture after the separation process. In order to prevent the end face of the separating device which is subsequently in contact with only one medium from being contaminated as the interior of the container is being filled with the mixture, the middle region of the separating device is provided with an orifice through which the mixture can be introduced into the rest of the interior of the housing container. During the subsequent separation process by centrifugation in the conventional manner using a radial centrifugal force (rcf) of 1,000 g to 5,000 g—where g represents the gravitational force and 1 g is a value of 9.81 m/s.sup.2—one medium separated from the mixture is transferred through the orifice in the separating device into the region disposed between the seal mechanism and the separating device and sinks in the direction of the closed end of the housing container as a result. In order to prevent the other medium disposed between the closed end and the separating device from passing through the orifice after the separation process and intermixing with the other separated medium again, a wider end stop is provided at a height corresponding to the usual remaining quantity of the other medium which is of a conical shape in the direction towards the closed end, by means of which the separating device runs onto the end stop which projects through the orifice. As soon as the external diameter of the end stop corresponds to the internal diameter of the orifice, the separating device remains in this position and the orifice is closed off by the stop as a result so that no exchange or intermixing can take place between the two media again. The disadvantage of this design is that it is necessary to manufacture a tube with an internally lying stop and the function whereby the media are separated is not reliable due to the orifice provided in the separating device. Furthermore, it is quite difficult to insert the separating device in the interior of the housing container subsequently.
Patent specification WO 96/05770 A1 discloses other container systems for centrifuging mixtures containing at least two different media which have to be separated, in which the housing container is closed off by a closure device at both end regions. A separating device in the form of a sealing disc is disposed in the interior and comprises a gel. During the centrifugation process, this gel plug migrates between the two different media separated from one another due to its specific weight, which in higher than the specific weight of the medium having the lower specific weight and lower than the specific weight of the medium with the higher specific weight, due to the centrifugal forces acting on it. Once positioned in this manner, therefore, the one medium of the mixture can be separated from the other. The disadvantage of this approach is that the shelf life is not enough for standard applications in many cases due to the fact that the separating device is provided in the form of a gel.
Other container systems with separating devices fitted in them are provided in the form of various valve arrangements and filter elements, as disclosed in patent specifications EP 0 311 011 A2, U.S. Pat. No. 3,897,343 A, U.S. Pat. No. 3,897,340 A, U.S. Pat. No. 4,202,769 A and U.S. Pat. No. 3,897,337 A.
Yet other container systems incorporating separating devices are known from EP 1 106 250 A2, EP 1 106 251 A2, EP 1 106 252 A2, EP 1 106 253 A2 and EP 1 107 002 A2, which disclose separating devices of various designs based on the principle whereby a component of the separating device deforms during the centrifugation process and on the basis of the density between the media to be separated.